This is a resubmission of our application for a small grant. Adherence with immunosuppressant medication following cardiothoracic transplantation (txp) is critical to long term survival and is problematic for a significant percentage of recipients. Cardiothoracic txp. is a life saving, though costly procedure; adherence is, therefore, an important public health care issue. Poor adherence after heart and/or lung txp. accounts for a significant proportion of mortality from graft failure; retransplantation, from a limited donor pool, is often the only option, and is not highly successful. While some progress has been made in identifying psychosocial predictors of non-adherence, findings across studies have been inconsistent. We propose that personality traits will provide keys to better understanding risk for poor adherence and may, therefore, inform design of more effective interventions to maximize compliance. Given the dearth of empirical work on the role of personality in txp, the proposed pilot research is designed to evaluate relationships between personality, medication adherence, and other putative risk factors for poor adherence within a longitudinal study of cardiothoracic txp. recipients who will be followed during their first 18 mos. post-txp. The proposed study is ancillary to a larger ongoing longitudinal study of adherence, quality of life, and emotional adjustment in this population. A projected sample of 176 subjects will be recruited from participants in the parent study; personality traits and the presence of personality disorder will be measured once in the proposed research, with the NEO--R and the Interpersonal Inventory of Personality, respectively, at 3-4 mos. post-txp; all other data will be collected in the parent study. Psychosocial predictors of adherence (intrapersonal and contextual) are measured at 2 mos. post-txp. Specifically, medication adherence is evaluated (with interview, self report, laboratory data, and electronic medication caps) at 6, 12, and 18 months post txp., and we will investigate prospective relationships between personality and subsequent adherence and the moderating effects of personality on the linkage between psychosocial variables and adherence; our data analyses will consider descriptive and bivariate associations and multivariate models of those effects. The goal of the proposed study is to provide clinicians with empirical data to better identify txp patients at risk of nonadherence in order to a) provide a way for them to target patients needing psychological/psychiatric referral and b) design more effective, economical interventions to maximize adherence with post-txp. medication regimes. The goal of the, a relatively new researcher, is to gain experience in order to develop more extensive study of psychological factors which better explain and predict treatment adherence after organ transplantation.